Synthesis And Application Of Amide Bridging Polymer Hole Transport Materials

The power conversion efficiency（PCE）of perovskite solar cells（PSCs）has rapidly increased from the initial 3%to 25.8%,which shows a good market application prospect.In PSCs,hole transport materials（HTMs）play an important role in extracting/transporting hole,inhibiting charge recombination and optimizing perovskite crystallization.Therefore,developing new HTMs with high hole mobility,well-matched energy level and passivation groups is expected to further improve the photovoltaic performance of PSCs.In this paper,we designed and synthesized seven kinds of new amide-bridged polymers HTMs using rigid binaphthalene group as the polymer skeleton,amide group as the flexible chain segment and passivation group.It was studied systematically the corresponding hole transport characteristics,interface passivation function and photovoltaic performance of HTMs.（1）Z7 and Z11 were synthesized by coupling reaction with triphenylamine groups substituted by methoxy（sulfur）group as electron donor,and binaphthyl group as central core.Subsequently,the two were reacted with thiophenic diacyl chloride to produce polymers EDOT-OMe,EDOT-SMe and T-SMe.Cyclic voltammetry（CV）results show that the energy levels of the three materials are well matched with that of perovskite materials.X-ray diffraction photoelectron spectroscopy（XPS）,X-ray diffraction（XRD）and scanning electron microscopy show that the amide bond effectively passivates the uncoordinated Pb²⁺and I^-in perovskite,which improves the quality of perovskite film.PSCs based on EDOT-OMe,EDOT-SMe and T-SMe have achieved PCEs of 20.23%,19.86%and 19.73%,respectively,which are comparable to the commercial HTM PTAA（19.68%）.Moreover,the PSCs with three amide polymers show better device stability than PTAA,showing promising industrial application.（2）The fluorinated compound Z14 was designed and synthesized.Z11 and Z14were reacted with trimesoylchloride to give the polyamides T-BS and T-FS with a network structure.PSCs with T-FS obtain an open-circuit voltage of up to 1.111V,which may be attributed to the negative shift of HOMO level of T-FS caused by the introduction of fluorine atom.However,the introduction of fluorine atom weakened the interaction between amide group and I^-in perovskite,reduced the passivation effect and affected the crystal quality of perovskite.By contrast,the perovskite prepared on the T-BS hole transport layer shows good crystal quality with few defects.Correspondingly,the PSCs with T-BS achieve a high fill factor of 0.843.The optimal PCE of T-BS-based devices reaches 20.86%,which is higher than that of T-FS（20.11%）.More important,the above PSCs maintained an over 80%of initial efficiency after 90 days,which shows significantly enhanced device stability compared to PTAA.（3）Indolo[3,2-a]carbazole and indeno[2,1-b]carbazole were used as electron donors to react with trimesoylchloride,respectively,to afford two kinds of reticular polyamide molecules T-BCZ and T-CZ.The important intermediates and target products were characterized by NMR.The influence of different electron donors on the materials characteristics of HTMs and the relevant device performance needs to be further explored.